Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the SnapshotAndReplace handoff behavior is used.(Inherited from Animatable.)

Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable.)

Coerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject.(Inherited from DependencyObject.)

Ensures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties.(Inherited from Freezable.)

Raises the Changed event for the Freezable and invokes its OnChanged method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties.(Inherited from Freezable.)

Verifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable.)

A timeline represents a segment of time. It provides properties that enable you to specify the length of that segment, when it should start, how many times it will repeat, how fast time progresses in that segment, and more.

Classes that inherit from the timeline class provide additional functionality, such as animation and media playback. The following are examples of some of the different types of specialized timelines available.

Animations: An AnimationTimeline is a type of timeline that produces output values. When you associate an animation with a property, the animation updates the property's value as it plays, thereby "animating" it. For an introduction to animations, see Animation Overview. For information about the different ways to apply animations, see the Property Animation Techniques Overview.

MediaTimelines: A MediaTimeline is a type of timeline that controls the playback of a media file.

ParallelTimelines: A ParallelTimeline is a type of timeline that groups other timelines.

Most timeline properties can be data bound or animated; however, because of the way the timing system works, data bound or animated timelines do not behave like other data bound or animated objects. To understand their behavior, it helps to understand what it means to activate a timeline.

When a timeline is applied, copies are made of the timeline and its child timelines. These copies are frozen (made read-only) and Clock objects are created from them. It's these clocks that do the actual work of animating the targeted properties. If a timeline was data bound or animated, a snapshot of its current values was made when its clock was created. Even though the original timeline might continue to change, its clock does not.

For a timeline to reflect data binding or animation changes, its clock must be regenerated. Clocks are not regenerated for you automatically. The following are several ways to apply timeline changes:

If the timeline is or belongs to a Storyboard, you can make it reflect changes by reapplying its storyboard using a BeginStoryboard or the Begin method. This has the side effect of also restarting the animation. In code, you can use the Seek method to advance the storyboard back to its previous position.

If you applied an animation directly to a property using the BeginAnimation method, call the BeginAnimation method again and pass it the animation that's been modified.

If you are working directly at the clock level, create and apply a new set of clocks and use them to replace the previous set of generated clocks.

A timeline's clock will only progress when there's an event hander associated with it or (in the case of an AnimationClock object) it is associated with a property. For this reason (and others), it's not recommended that you use a Timeline as a timer.